SACRAMENTO, Calif. — On the first Sunday in January, Tom Hein stood on the tarmac in Humboldt County, in northern California, watching an air tanker come in for a landing. The Grumman S-2T was one of three tankers working to put out the “Red Fire,” a blaze that caught on a mountain ridge the previous day.

Hein snapped a picture of the tanker and the fire in the distance on his camera phone, which he sent to his boss: “January in Rohnerville,” the caption read.

The fire, Hein said later, is one he will remember. It wasn’t the largest fire of the year, and it didn’t claim any lives. But it burned 333 acres in Humboldt County — one of the wettest places in America. The county, which averages more than 100 inches of rain every year, is dry as a bone.

“We’re seeing summertime weather conditions in January,” Hein said as two of his crews continued to mop up the smoking remnants of the Red Fire. “If we don’t get some rain now, just imagine what the summer is going to be like.”

Across the Western United States, officials tasked with fighting forest fires worry that a confluence of factors, including climate change and human development, are conspiring to create conditions ripe for a landmark fire year. That would mean hotter fires that burn longer and threaten more homes, sapping already-strained budgets and putting at risk the lives of thousands of firefighters.

President Barack Obama was traveling to Fresno, Calif., Friday to meet with farmers and others coping with the impact of the ongoing drought.

“Things really are at critical levels in parts of the West, and while we’re hoping and praying for rain and some moisture, we are very worried,” said Tom Harbour, the U.S. Forest Service’s National Director of Fire and Aviation Management.

The lack of precipitation has already become a national emergency. A three-year drought that has spread across the West has dried out the fuel — trees, shrubs and grasses — that feeds fires. The drought is particularly acute in California, where the snowpack in the Sierra Nevada mountains is at just 12 percent of the annual average. Several rural California counties are within a few months of running out of water altogether.

Snowpack across the Cascades in Washington and Oregon is also far below normal levels, according to data maintained by the Water and Climate Center, a division of the U.S. Department of Agriculture based in Portland, Ore.

The severity and breadth of fire activity has increased dramatically in recent decades. More man-made structures are burning now than ever before, and more fire fighters are dying.

In the 1980s, wildfires burned an average of 2.98 million acres every year. Between 2003 and 2012, an average of 7.26 million acres burned per year. Parts of the West are experiencing the driest 15-year period in 1,200 years.

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“In my conversations with officials from the states, they are all dealing with climate change. I can’t recall a conversation that has been any kind of a debate about whether this is effecting our landscapes. I don’t think there is a debate,” Interior Secretary Sally Jewell said in a recent interview. “They’re dealing, in these Western states, with some real extremes.”

The consequences of climate change encourage wildfires in three ways, firefighters and policymakers say. First, even modest rises in temperatures change forest ecologies and allow invasive species to take root. Second, changing weather patterns can stem much-needed precipitation. And third, global warming is extending the fire season.

In the last four decades, the average fire season has grown by 78 days — more than a fifth of a year. If temperature trends continue, the Intergovernmental Panel on Climate Change warns, the fire season across Canada, Russia and the United States could expand by another month over the next five decades. While winter was once the time when fire agencies repaired aircraft and cut seasonal staff, states like California have had to keep their aircraft operating all year round.

Climate scientists believe a reduction in polar ice is changing atmospheric circulation patterns, which could contribute to a slowing of the jet stream, contributing to colder, wetter weather in the Eastern United States and more persistently dry conditions in the West.

Rising temperatures have aided invasive pests like the mountain pine beetle in the Pacific Northwest and the goldspotted oak borer in Southern California, which turn living trees that could survive a fire into dead, dry, 20-foot tall matchsticks. Scientists hope this winter’s freezing temperatures have temporarily stemmed the spread of those bugs, though there is no way to be certain.

Higher temperatures means plant life once confined to more southern climates is creeping northward. Those new species can burn faster and at higher intensity than the species they are driving out.

“As the temperature has gradually changed, we’re kind of seeing this changing vegetation dynamic,” said Ken Pimlott, director of the California Department of Forestry and Fire Protection, known as CalFire. “We’re seeing trees throughout the foothills here, what’s called grey pine, they’re slowly dying off. They’re being replaced by brush and vegetation. That kind of a change leads to more flammable vegetation in these traditional elevations that would normally be cooler, more moist.”

Fire is a natural phenomenon. It sweeps through forests on a regular basis, clearing out debris and dead foliage, refreshing vegetation and revitalizing the land. But the fire cycle is accelerating, especially in the Rocky Mountains. Reduced precipitation means forests that once burned every 100 to 150 years are now burning much more frequently. The climate, which for millenia has acted as a curb on fire activity, is becoming an accelerant.

“At some point in the not so distant future, the next few decades probably, climate will no longer be the overriding constraint on the system’s ability to burn,” said Anthony Westerling, an associate professor at the University of California Merced and a faculty member at the Sierra Nevada Research Institute. “It will be dry enough in most years. The constraint will be how much fuel is on the ground.”

The federal agency at the center of the fight to suppress wildfires is the National Interagency Fire Center, headquartered in a low, concrete two-story building next to the international airport in Boise, Idaho. It overlooks a small memorial park dedicated to fallen firefighters.

In Washington, Harbour wakes early to read reports on weather patterns and other data coming from Boise. And in state capitals across the country, fire chiefs like Pimlott manage their land, and their fire crews, while interacting with their federal partners.

Between the federal, state and local offices, managers oversee 56,000 wildland fire fighters, with help from about 100,000 local fire fighters dedicated to protecting man-made structures. At the height of fire season, those numbers swell.

Their jobs are getting harder. The recovering economy is driving a new housing boom in the buffer zone between unoccupied forest land and human settlements. As more subdivisions crop up in the suburbs of Seattle and Sacramento and in the resort towns of Sun Valley, Idaho, and Jackson Hole, Wyo., more than half the fires fought by the government now involve human structures.

In parts of California, the cost of defending a single home can run as high as $600,000 — far more than many of the homes are actually worth. And while homeowners are able to get out before a fire sweeps over them, the firefighters who have to defend those homes wade into danger.

Last year was especially brutal: In June 2013, 19 members of the Prescott Fire Department’s Granite Mountain Hotshots died after being trapped by a fast-moving fire while trying to protect human structures in Yarnell, a tiny town of 649 people. It was the worst single incident for wildland firefighters since a 1933 blaze in California killed 25.

To reduce the threat to firefighters, some state and local agencies have made clear they won’t defend homes in dangerous areas. Kathy Clay, the fire marshal in Jackson Hole, Wyo., says she won’t send fire fighters into what she calls “suicide subdivisions” — areas accessible by only one road, situated atop a hill or ridge and surrounded by conifers that, in a rapidly-moving fire, could cut off routes of retreat.

Her decision represents a broader shift in policy being adopted by other fire agencies: Their firefighters will defend lives, but not necessarily homes.